User Geo Update Channel

Closes #7
- Adds ParseBroadcastReceiver to list of manifest services
- Only saves user geo if it changes
- Publishes the user's geo to a channel, if it changes
- Refactors RequestMapActivity to use the onLocationChanged method when setting the current user's location
- Caches actionBar into a field
- Sets a default push callback for the phone (necessary to receive events)
- Creates the UserUpdateChannel: a way to subscribe and publish user events
- Creates a generic JsonDataReceiver (should we need to receive other push notification types)
- Creates MapUtil to consolidate common map manipulations
- Creates PushUtil, an interface between activities and the parse push API
- Adds a few new permissions to the manifest for push notifications